Images
People with visual impairments, who are most likely using screen readers, cannot “see” images. They rely on alternative text that the screen reader reads out to them.
Do
- All images need to have an alternative description or be marked as decorative
Do Not
- Put important information into images alone, provide a text version as well.
- Scanned documents are essentially images and the information will not be picked out by screen readers, avoid using these, especially publishing them on websites.
- Use text boxes - These are treated as images so any text in them would be missing for assistive technology.
- Use images or graphics with lots of text - alt text space is limited
- Auto-generated alt text
Alternative text settings
Some versions of Word will have a ‘generate alt text’ option, but this often produces inconsistent or unreliable content so should not be used.
You can switch off automatic alt texts by going to File>Options>Accessibility then un-tick the box under Automatic alt texts
How to add Alternative Text to an image in M365
- Right click on an image
- Edit Alt Text
- Type a description or mark as decorative
- If using the Accessibility Checker: Select “Alt Text” and add your text in here
Decorative images are images just used to brighten up the presentation and don’t provide any value to the content of the document. If these images are purely for decoration you can mark this as such in the Alt text tool. This means a screen-reader will bypass this information.
How to write suitable alt text
When writing an Alt Text, there are no exact rules, but you need to provide everything that someone who can see the image/graphic would see or understand from viewing it. Try thinking about explaining what the image looks like to someone over the phone who can’t physically see it.
Infographics
- If the image is providing information, you need to write out an alt text to accurately describe all the information in it. It will also be a substitute if the page does not load the image correctly.
- Avoid overly long text graphics/alt texts. If the text is more than a sentence or two, you should either include the graphic but mark it as decorative and include the text on the page, or remove the graphic completely and just type the text onto the page
Alt text: Did you know? We look after nearly 14,000 lighting units – including street lights, bollards and road signs.
Graphs and charts
- Avoid generic descriptions like “graph showing Work Week Hours”
- Specify the type of graph (bar chart, pie chart, etc) and variables mentioned
- Highlight the main trends and patterns.
- If the graph is complex, then mark the image as decorative and add a text description to the page of the document instead of an alt text
Alt text: Pie chart of breakdown of a time spent on tasks for a fake working week. Most time is spent in meetings with clients at 38% with Morning planning and end of day round-up taking up least time at 7% each.
Decorative
If an image provides no information or context then it can be marked as decorative:
Video
Videos and presentations should have a transcript provided. This allows anyone who is deaf or has a hearing impairment to access the information but it is also beneficial to many others.
- There are many people that choose to add subtitles to assist with comprehension when watching a TV programme.
- In a busy office we very often choose to read the information rather than listen to it.
This means making videos and presentations as accessible as possible can help out everyone.
If you are adding videos to YouTube there should be an option for subtitles so the user can enable these. You can read more about PowerPoint presentations here.
For a more detailed explanation please refer to the Microsoft guidelines on how to make images accessible.